Quantification of intravenous contrast-enhanced Doppler power spectrum in the rabbit carotid artery

1995 ◽  
Vol 21 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Donald P. Frush ◽  
Diane S. Babcock ◽  
Keith S. White ◽  
Lori L. Barr
Keyword(s):  
Carotid Artery ◽  
Power Spectrum ◽  
Intravenous Contrast ◽  
Rabbit Carotid Artery ◽  
Contrast Enhanced ◽  
Doppler Power

High Resolution Contrast-Enhanced MR Angiography in the Evaluation of Rabbit Carotid Artery

2005 ◽  
Vol 18 (5-6) ◽  
pp. 529-536
Author(s):  
R.-H. Wu ◽  
D.F. Kallmes
Keyword(s):  
High Resolution ◽  
Image Quality ◽  
Carotid Artery ◽  
Mr Angiography ◽  
Flip Angle ◽  
Acquisition Time ◽  
Pixel Size ◽  
Rabbit Carotid Artery ◽  
Contrast Enhanced ◽  
Venous Contamination

This study compared a high resolution contrast-enhanced MR angiography (MRA) sequence to conventional contrast-enhanced MRA sequence for imaging of rabbit carotid artery. Fifteen rabbits underwent an evaluation using both high resolution contrast-enhanced MRA sequence and conventional contrast-enhanced MRA sequence. Siemens 1.5 Tesla Magnetom Vision system was utilized. The parameters of high resolution sequence were: TR/TE= 6.2/2.0 msec, flip angle 25°, matrix 130×512, pixel size 0.96×0.49 mm, partition thickness 1.58 mm, acquisition time 24 sec. The parameters of conventional sequence were: TR/TE=3.8/1.4 msec, flip angle 35°, matrix 110×256, pixel size 1.48×1.02 mm, partition thickness 2mm, acquisition time 10 sec. Maximum intensity projection (MIP) images were created. Both original single slices and MIP images were used for image quality evaluation. Contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), distinctness of artery edge, and venous contamination were analyzed for both techniques. Higher average CNR and SNR were obtained with high resolution contrast-enhanced MRA, compared to average CNR and SNR with conventional contrast-enhanced MRA. The differences were statistically significant (P<0.01). The artery edge with high resolution method was more distinct than conventional method. Jugular venous contamination was found in five of 15 cases with high resolution contrast-enhanced MRA and in four of 15 cases with conventional contrast-enhanced MRA. High resolution contrast-enhanced MRA has significant potential for high quality noninvasive vascular imaging. The image quality with high resolution contrast-enhanced MRA sequence is better than conventional contrast-enhanced MRA sequence.

Effect of atherosclerosis on responses of the perfused rabbit carotid artery to human platelets.

1992 ◽  
Vol 12 (10) ◽  
pp. 1206-1213 ◽  
Author(s):  
S Kaul ◽  
R C Padgett ◽  
B J Waack ◽  
R M Brooks ◽  
D D Heistad
Keyword(s):  
Carotid Artery ◽  
Human Platelets ◽  
Rabbit Carotid Artery

scholarly journals An Estimator for Weather Radar Doppler Power Spectrum via Minimum Mean Square Error

2021 ◽  
pp. 1-16
Author(s):  
Eiichi Yoshikawa ◽  
Naoya Takizawa ◽  
Hiroshi Kikuchi ◽  
Tomoaki Mega ◽  
Tomoo Ushio
Keyword(s):  
Power Spectrum ◽  
Mean Square Error ◽  
Minimum Mean Square Error ◽  
Weather Radar ◽  
Mean Square ◽  
Doppler Power

Enhanced role of K+ channels in relaxations of hypercholesterolemic rabbit carotid artery to NO

1995 ◽  
Vol 269 (3) ◽  
pp. H805-H811 ◽  
Author(s):  
S. Najibi ◽  
R. A. Cohen
Keyword(s):  
Carotid Artery ◽  
Sodium Nitroprusside ◽  
Channel Blocker ◽  
Isometric Tension ◽  
K Channel ◽  
K Channels ◽  
Rabbit Carotid Artery ◽  
Cyclic Monophosphate ◽  
Endothelium Dependent Relaxation

Endothelium-dependent relaxations to acetylcholine remain normal in the carotid artery of hypercholesterolemic rabbits, but unlike endothelium-dependent relaxations of normal rabbits, they are inhibited by charybdotoxin, a specific blocker of Ca(2+)-dependent K+ channels. Because nitric oxide (NO) is the mediator of endothelium-dependent relaxation and can activate Ca(2+)-dependent K+ channels directly or via guanosine 3',5'-cyclic monophosphate, the present study investigated the role of Ca(2+)-dependent K+ channels in relaxations caused by NO, sodium nitroprusside, and 8-bromoguanosine 3',5'-cyclic monophosphate (8-Brc-GMP) in hypercholesterolemic rabbit carotid artery. Isometric tension was measured in rabbit carotid artery denuded of endothelium from normal and hypercholesterolemic rabbits which were fed 0.5% cholesterol for 12 wk. Under control conditions, relaxations to all agents were similar in normal and hypercholesterolemic rabbit arteries. Charybdotoxin had no significant effect on relaxations of normal arteries to NO, sodium nitroprusside, or 8-BrcGMP, but the Ca(2+)-dependent K+ channel blocker significantly inhibited the relaxations caused by each of these agents in the arteries from hypercholesterolemic rabbits. By contrast, relaxations to the calcium channel blocker nifedipine were potentiated to a similar extent by charybdotoxin in both groups. In addition, arteries from hypercholesterolemic rabbits relaxed less than normal to sodium nitroprusside when contracted with depolarizing potassium solution. These results indicate that although nitrovasodilator relaxations are normal in the hypercholesterolemic rabbit carotid artery, they are mediated differently, and to a greater extent, by Ca(2+)-dependent K+ channels. These data also suggest that K+ channel-independent mechanism(s) are impaired in hypercholesterolemia.

scholarly journals MRA Mapping and Selective Embolization of a Large Uterine Cavity Pseudoaneurysm at 20 Weeks of Gestation

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Jean V. Storey ◽  
Timothy B. Dinh ◽  
Deirdre M. McCullough ◽  
Steven H. Craig ◽  
Christian L. Carlson
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Angiography ◽  
Mortality Risk ◽  
Vascular Malformations ◽  
Uterine Cavity ◽  
Massive Hemorrhage ◽  
Fetal Mortality ◽  
Intravenous Contrast ◽  
Selective Embolization ◽  
Contrast Enhanced

Antepartum uterine cavity pseudoaneurysm rupture can cause massive hemorrhage with high maternal and fetal mortality risk. Invasive placentation can predispose to vascular malformations. We present a novel use of macrocyclic intravenous contrast-enhanced magnetic resonance angiography for preprocedure planning followed by selective low radiation embolization of a uterine cavity pseudoaneurysm in the setting of invasive placentation at 20 weeks of gestation. To our knowledge, this is the first reported case of uterine cavity pseudoaneurysm successfully mapped with MRA and treated with embolization at 20 weeks of gestation.

Abstract 11733: Assessment of Carotid Plaque Neovascularization Using Quantitative Analysis of Contrast-Enhanced Ultrasound Imaging is Useful for Risk Stratification in Patients With Coronary Artery Disease

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jun Nakamura ◽  
Takamitsu Nakamura ◽  
Juntaro Deyama ◽  
Daisuke Fujioka ◽  
Ken-ichi Kawabata ◽  
...  
Keyword(s):  
Risk Factors ◽  
Heart Failure ◽  
Quantitative Analysis ◽  
Carotid Artery ◽  
Carotid Plaque ◽  
Contrast Enhanced Ultrasound ◽  
Baseline Model ◽  
Contrast Enhanced ◽  
Traditional Risk Factors ◽  
Artery Disease

Introduction: Extensive neovascularization in atherosclerotic plaque has been shown to be associated with plaque progression and instability, leading to atherosclerotic cardiovascular events. Contrast-enhanced ultrasound (CEUS) of the carotid artery is a potential technique for imaging plaque neovascularization. Hypothesis: Assessment of intra-plaque neovascularization of the carotid artery using quantitative analysis of CEUS provides prognostic information in patients with coronary artery disease (CAD). Methods: This study included 206 patients with stable CAD and with carotid intima-media thickness (IMT) > 1.1 mm. They underwent a CEUS examination of the carotid artery and were followed-up prospectively for < 38 months or until a cardiac event (cardiac death, non-fatal myocardial infarction [MI], unstable angina pectoris [uAP] requiring unplanned coronary revascularization, or heart failure requiring hospitalization). The degree of contrast signals measured within the carotid plaque after the intravenous injection of contrast material was quantified by calculating the increase in mean gray scale level within the region of interest of the carotid plaque, expressed as plaque enhanced intensity. Results: During the follow-up period (3 - 38 months, mean 22.8 ± 11.8 months), 31 events occurred (2 cardiac deaths, 7 non-fatal MIs, 16 uAP, and 6 heart failure). Multivariate Cox proportional hazards analysis showed that plaque enhanced intensity was a significant predictor of cardiac events independent of traditional risk factors (HR, 1.52; 95% CI, 1.20 - 1.94; p = 0.001). The addition of plaque enhanced intensity had a significant incremental effect on the area under the ROC curve (AUC) generated using baseline model of traditional risk factors (AUC: baseline model 0.69 vs. baseline model + plaque enhanced intensity 0.78, p = 0.03). The addition of the plaque enhanced intensity to the baseline risk factors resulted in net reclassification improvement (NRI) and integrated discrimination improvement (IDI) (NRI 0.58, p = 0.003; and IDI 0.078, p = 0.03). Conclusions: The assessment of carotid plaque neovascularization using quantitative analysis of CEUS may be useful for risk stratification in patients with CAD.

The Antiaggregating and Antithrombotic Activity of Clopidogrel Is Potentiated by Aspirin in Several Experimental Models in the Rabbit

1998 ◽  
Vol 80 (09) ◽  
pp. 512-518 ◽  
Author(s):  
Frédérique Dol ◽  
André Bernat ◽  
Robert Falotico ◽  
Alain Lalé ◽  
Pierre Savi ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Carotid Artery ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Experimental Models ◽  
Arteriovenous Shunt ◽  
Thrombotic Occlusion ◽  
Antithrombotic Activity ◽  
Rabbit Carotid Artery ◽  
Antithrombotic Efficacy

SummaryIt is unknown whether the addition of aspirin might increase both the efficacy and the potency of clopidogrel, a potent and selective ADP blocker. For that purpose, the efficacy of clopidogrel (1–20 mg/kg, p.o.) administered orally to rabbits alone or in combination with aspirin (0.1–10 mg/kg, p.o.) was determined in several experimental models. A potent synergistic effect of the clopidogrel/aspirin association was demonstrated with regard to collagen-induced platelet aggregation measured ex vivo. Similarly, aspirin potentiated the antithrombotic activity of clopidogrel measured with regard to experimental thrombosis induced by a silk thread or on stents placed in an arteriovenous shunt, thrombus formation following electrical stimulation of the rabbit carotid artery and with regard to 111In-labeled platelet deposition on a stent implanted in an arteriovenous shunt or on the subendothelium following air drying injury of the rabbit carotid artery. A similar potentiating effect of aspirin was obtained with regard to myointimal proliferation (restenosis) in the femoral arteries of atherosclerotic rabbits which occurred as a consequence of stent placement. The clopidogrel/aspirin combination showed only additive-type effects on bleeding time prolongation induced by ear transection in the rabbit, therefore showing that combined inhibition of cyclooxygenase and ADP‘s effects provide a marked enhanced antithrombotic efficacy. Such a combination may provide substantial protection against platelet aggregation leading to thrombotic occlusion at sites of endothelial injuries and coronary artery stenosis in humans.

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